CLIF captures detailed ICU data including ventilator settings throughout the stay (FiO2, PEEP changes), vasoactive drug titrations, and other critical parameters. While the schema supports high-frequency data, current federated analyses focus on clinically meaningful time intervals that balance detail with practical research needs.

A lead principal investigator (PI) originates a project idea, specifies the required cohort and CLIF tables for the project, and then develops analytic code written using their local CLIF database. The CLIF consortium then runs the script and returns aggregate results to the PI. The PI compiles the aggregate results for publication.

At no point is patient-level (i.e. “row-level”) data exchanged between sites, unless there is a specific Data Use Agreement (DAU) that permits this for specific combinations of consortium sites and directionality. You can submit your project idea here!

The current CLIF framework is for standardized longitudinal ICU data elements (e.g. labs, vitals, ventilator settings, medication doses, and flowsheet documentation). We believe the clinical context defined by these standardized minimum Common ICU Data Elements (CDE) are essential for the proper interpretation of multi-modal data such as clinical notes and imaging results.

Once CLIF is mature for these standardized data elements, we plan to represent these multi-modal data.

Established open-source CDMs such as the OMOP take on data harmonization and standardization challenge for the entire EHR. The work of the Observational Health Data Sciences and Informatics (OHDSI) community has been a guiding force for the CLIF consortium throughout CLIF’s development. However, the extract-transform-load (ETL) to a CDM is a major data engineering challenge, and data elements essential for the study of critical illness typically are not prioritized. Local CDM instances often completely omit granular critical illness data elements, such as ventilator settings for patients suffering from respiratory failure.

CLIF is designed for critically ill hospitalized adults and does not represent outpatient encounters. The patient, hospitalization, and admission_diagnosis table summarize information about the patient on admission to the hospital. CLIF could be used as one part of a larger EHR study that requires outpatient data from before the admission.

CLIF is currently not linked to established interoperability standards like Health Level Seven (HL7) Fast Healthcare Interoperability Resources (FHIR). Future data engineering directions include the development of HL7 FHIR queries to generate real-time CLIF tables.

The CLIF consortium is committed to the responsible conduct of research. Each consortium site has independent IRB approval or an exemption for each CLIF project they run on their local CLIF database.

The consortium is aware of the NIH Single Institutional Review Board (IRB) policy and planning to adhere to this policy for future NIH-funded projects using the consortium.

We're excited to support innovative critical care research projects! Please email us at clif_consortium@uchicago.edu with a brief description of your project. Our scientific committee reviews proposals and can help connect you with participating sites and resources.